Description
Title of Invention: OPTIMIZED USER EQUIPEMENT
RELAYING
Technical Field
[0001] The present invention generally relates to access networks and more particularly to
relaying provided by a terminal used as a relay node. Such a terminal is called
hereafter "user equipment relay" (UER).
It finds applications, in particular, in Radio Access Network (RAN) where base
stations cannot cover some geographical areas in a network and further relay means are
needed to ensure the transmission of a communication between a base station and a
target terminal or a target node, called hereafter "target" (UET).
Background Art
[0002] The present invention can find applications related to relaying aspects for commu
nication via a mobile device used as a relay node in a network, such as, for example a
3GPP LTE network.
[0003] LTE (for "Long Term Evolution"), marketed as 4G LTE, is a standard for wireless
communication of high-speed data for mobile phones and data terminals. It is based on
older network technologies (such as the universal mobile telecommunication system
(UMTS)), increasing the capacity and speed using a different radio interface together
with core network improvements. Optimized components from the UMTS used in the
LTE are signalled by the prefix "evolved". For example, a base station transmitting
communications as a NodeB in the UMTS is called an "eNodeB" in the LTE.
[0004] Such an evolution has an influence on the communication protocol layers stack also.
In the 3GPP LTE network, it can be spitted into seven different layers constituting the
Open Systems Interconnection (OSI) model. It is recalled that an OSI model is a pre
scription of characterizing and standardizing the functions of a communications
system. Similar communication functions are grouped into logical layers. A layer
serves the layer above it and is served by the layer below it.
[0005] Every layer has to offer the upper layers the service of information transmission
between a user equipment (UE) and the network. Therefore, upper layers need
channels from the lower layers to communicate with the UE. For example, Layer 3
offers higher layers channels that are called radio bearers (RB) for the transfer of
network data. Network data can be either control data for the configuration of the
network or user data (for example telecommunication data). Layer 2 offers logical
channels onto which radio bearers can be mapped. Therefore, the service access points
between Layer 2 (reference "L2" in Fig. 3) and upper layers are RBs. A more detailed
description of such OSI layers will be given with respect to Fig. 3 presented hereafter.
[0006] In fact, Fig. 2 illustrates a structure of a radio interface protocol between the terminal
and the E-UTRAN according to the 3GPP radio access network standards. As shown in
Fig. 2, the radio interface protocol has vertical layers including a physical layer, a data
link layer, and a network layer, and has horizontal planes including a user plane
(U-plane) for transmitting user data and a control plane (C-plane) for transmitting
control information.
[0007] The user plane is a region that handles traffic information with the user, such as voice
or Internet protocol (IP) packets. The control plane is a region that handles control in
formation for an interface with a network, maintenance and management of a call, and
the like.
[0008] The protocol layers in Fig. 2 can be divided into a first layer (LI), a second layer
(L2), and a third layer (L3) based on the three lower layers of an open system inter
connection (OSI) standard model. The first layer (LI), or the physical layer, provides
an information transfer service to an upper layer by using various radio transmission
techniques. The physical layer is connected to an upper layer, called a medium access
control (MAC) layer, via a transport channel.
[0009] The MAC layer and the physical layer exchange data via the transport channel. The
second layer (L2) includes a MAC layer, a radio link control (RLC) layer, a broadcast/
multicast control (BMC) layer, and a packet data convergence protocol (PDCP) layer.
The MAC layer handles mapping between logical channels and transport channels,
and provides allocation of the MAC parameters for allocation and re-allocation of
radio resources. The MAC layer is connected to an upper layer, called the radio link
control (RLC) layer, via a logical channel.
[0010] Various logical channels are provided according to the type of information
transmitted. In general, a control channel is used to transmit information of the control
plane, and a traffic channel is used to transmit information of the user plane.
[001 1] A logical channel may be a common channel or a dedicated channel depending on
whether the logical channel is shared. Logical channels include a dedicated traffic
channel (DTCH), a dedicated control channel (DCCH), a common traffic channel
(CTCH), a common control channel (CCCH), a broadcast control channel (BCCH),
and a paging control channel (PCCH) or a shared channel control channel.
[0012] The BCCH provides information including information utilized by a terminal to
access a system. The PCCH is used by the UTRAN to access a terminal.
[0013] In a 3GPP LTE network, a network node such as the evolved NodeB (eNB) has the
role of transmitting/receiving the data and signalling from the core network (CN) to the
User Equipments (UEs) which are under its radio cell coverage, or from the UEs to
CN. A user equipment (UE) is a terminal such as a telephone, a smartphone, a
connected computer, a tablet, etc.
[0014] Fig. 1 gives an overview of the network between the UE and the CN. Furthermore,
UEs need to transmit/receive data and/or signalling to/from the eNB whenever a com
munication is required (e.g. to register, update registration, establish a data session or a
voice call). For example, in Fig. 1, UEA1 and UEA2 are located within cell A and are
therefore using eNBA to communicate with the network.
Summary of Invention
Technical Problem
[0015] However, due to some factors (e.g. environment, path loss, power limitation), the cell
coverage may be limited or there may be some regions where the signals from the eNB
cannot be decoded by the UEs. For example, in Fig. 1, UE is not located within a cell.
This UE is therefore out of the network's coverage. Moreover, since eNB gathers all
communication, its resources may become limited or insufficient. Consequently, there
may be fewer services for users and the ongoing communication/applications may
suffer of latency for instance.
[0016] In order to deal with the problems quoted before, the 3GPP group introduced Relay
Node entities (which are usually Relay Base Stations) in the following document:
Technical Specification Group Radio Access Network; Evolved Universal Terrestrial
Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network
(E-UTRAN) - Overall description.
[0017] Instead of having UEs to eNB direct communication, transmitted data and/or
signalling can pass through another node (the Relay Nodes) before reaching the target
node (now called the Donor eNB or DeNB). For eNB to UEs communication,
transmitted data and/or signalling can pass through the Relay Nodes before reaching
the UEs. The Relay Node (RN) can be fixed or mobile.
[0018] With such RN, the RN's equipment capabilities (such as memory or processing c a
pacities) are significantly consumed. Therefore, if such an RN were also fully used as a
UE, the user might suffer from a lack of his equipment capabilities. As the data
relaying is done at the IP level layer (IP for "Internet Protocol") which is a layer above
L2 as shown in Fig. 3, the equipment has to encode and decode information at IP level
if it were used as a relay. Thus, the problem would be moved simply from the eNB to
the UE and induced latency also.
Solution to Problem
[0019] The invention aims to improve the situation.
To address these needs, a first aspect of the present invention relates to a method for
relaying a communication in a network, wherein a user equipment relays a commu
nication between a network node entity and a target entity, the method including the
steps: generating a logical channel at least between the user equipment relay and the
target entity, and assigning at least one identifier to said logical channel, and upon
reception from the network node entity, at the user equipment relay, of data received
with said identifier, the user equipment relay forwards the received data to the target
entity.
[0020] The data to be communicated can be control data (signalling data for example) and/or
user data (voice and/or multimedia and/or content data for example).
[0021] The network can be an LTE network (as described in the examples hereafter), but
also any network.
[0022] The user equipment relay can be a telephone, a smartphone, a tablet, a computer, a
game station, or any device which is able to relay data between two network entities.
[0023] The network node entity can be for example a base station, an eNodeB in a LTE
network, but also another user equipment relay in a hoping scheme (several user
equipment relays to forward a communication to a target).
[0024] The target entity can be another user equipment, but possibly also a base station (or
more generally a network node) for example in a case where a communication between
two base stations becomes impossible and a relay from a user equipment is needed.
[0025] Therefore, such a relaying function using a user equipment can be a solution to
improve the cell coverage or provide the network with offloading alternative.
[0026] Of course, the network node entity is deemed to have a radiofrequency link (direct or
indirect link) with the user equipment relay, and the user equipment relay is deemed to
have a radiofrequency link with the target entity.
[0027] In an embodiment, reversely, the method can further include the steps: generating a
logical channel between the user equipment relay and the network node entity, and
assigning an identifier to said logical channel, and upon reception from the target
entity, at the user equipment relay, of data received with said identifier, the user
equipment relay forwards the received data to the network node entity.
[0028] The terms "generating a logical channel" can be understood, in a general way, as
aiming inter alia a declaration of a radiofrequency link to root data through that link. In
a specific embodiment, at least one radio bearer between the user equipment relay and
the target entity can be configured with generating the aforesaid logical channel.
[0029] In that embodiment, the step of generating said logical channel can further include
configuring: at least one radio bearer between the user equipment relay and the target
entity, and optionally, a radio bearer between the user equipment relay and the network
node entity.
[0030] In an embodiment, the method can further include the step of receiving from the
network node entity the identifier of the logical channel, and parameters for setting up
said radio bearers.
[0031] Therefore, a new information element (e.g. the logical channel identifier inter alia)
can be created for the establishment of the radio bearer(s) used for the relay, and that
new information element can be included in a message which can be usually intended
for the establishment of the radio bearers used without relay between a user equipment
and a network node entity.
[0032] Such a message can be advantageously, in an embodiment, of a type of a "Radio
Resource Control" signalling message sent from said network node entity to the user
equipment relay. That kind of message already exists and is usually sent from a base
station (e.g. an eNodeB in a LTE network). It can thus include the logical channel
identifier(s) and radio bearer(s) parameters.
[0033] More particularly, the signalling message can be a "Radio Resource Control
Connection Reconfiguration" message.
[0034] Such a message can be received directly from a base station if this base station is the
aforesaid network node entity, or can be either received from another network node
entity (e.g. another user equipment relay in a hoping scheme) which simply relays that
message.
[0035] Moreover, according to an embodiment of the invention, data are relayed through the
user equipment relay according to a protocol of a layer 2 in an Open Systems Inter
connection model (OSI).
[0036] Therefore, in a general way, there is no need to decode and encode data received at
the user equipment and a simple identifier of a logical channel added to the received
data is sufficient for the user equipment to make it understand that it should simply
relay the received data through that logical channel.
[0037] Therefore, there is no need to carry out deep modifications of already existing
systems to perform the relay with a user equipment thanks to these embodiments of the
invention.
[0038] In fact, in a first embodiment data can be relayed through the user equipment relay
according to a protocol of an above MAC layer, and the logical channel identifier can
be included in a MAC Protocol Data Unit.
[0039] In a second embodiment, data are relayed through the user equipment relay
according to a protocol of an above RLC layer, and the logical channel identifier can
be included in a RLC Protocol Data Unit. The choice between the first and the second
embodiment can be decided on the basis of optimization purpose and/or according to
the capabilities and/or construction of equipments in the network. In a possible em
bodiment, a dynamic choice can be performed (for example according to a user
equipment relaying capabilities) and the protocol layer to be used for relaying at the
user equipment relay can be configured by the network (for example by the network
node entity if it is a base station, or by the core network).
[0040] In an embodiment, the dynamic choice between "above-mac" and "above-RLC" con
figurations can be performed thanks to a transmission of information related to a used
protocol layer configuration, such information being included in a message of a type of
a "Radio Resource Control" signalling message sent from the network node entity to
the user equipment relay, for example a "Radio Resource Control Connection Recon
figuration" message as explained above.
[0041] The present invention aims also at a computer program product, including in
structions for performing the method according to any embodiment indicated above,
when run by a processor.
[0042] For example, the present invention can be performed in a user equipment which can
be suitably programmed to that end. At least a part of the instructions of the aforesaid
program product can be stored in a ROM memory and run by a processor of the user
equipment.
[0043] The invention aims thus at a user equipment also, including means for relaying a
communication in a network (radiofrequency means such as one or several antennas
and communication interfaces), between a network node entity and a target entity, the
user equipment further including means (e.g. at least a storage memory and a
processor) at least for:
upon reception from the network node entity of data received with an identifier of a
logical channel between the user equipment relay and the target entity, the user
equipment relay forwards the received data to the target entity.
[0044] Therefore, the user equipment relay includes specific means for interpreting the
logical channel identifier, so as to forward directly data received from the network
node entity and intended to the target entity (without decoding/encoding).
[0045] In an embodiment, the user equipment relay can further include means for generating
a logical channel at least between the user equipment relay and the target entity, and
assigning at least one identifier to that logical channel.
[0046] In another embodiment, a base station can generate the logical channel and can send
data related to the logical channel to the user equipment relay so as to interpret the
logical channel identifier as explained above.
[0047] Therefore, the present invention aims also at a base station including means for de
termining a user equipment for relaying a communication in a network between a
network node entity and a target entity, the base station including means for de
termining further a logical channel between the user equipment relay and the target
entity, and assigning at least one identifier to said logical channel.
[0048] Such a base station (e.g. an eNodeB in a LTE network) can be used for determining a
best user equipment for relaying a communication to a target. Furthermore, the base
station can also calculate the radio bearers parameters and define, finally, the logical
channel for the relay.
[0049] The base station according to the invention can further include means for sending a
"Radio Resource Control" signalling message including said identifier, intended to the
user equipment relay, according to an embodiment indicated above.
[0050] The calculations of the radio bearers parameters and more generally of the logical
channels configurations can be performed also at the core network and the present
invention aims thus also at a core network including means for determining data
related to at least a logical channel between a user equipment relay and a target entity,
the user equipment being intended to be used as a relay for relaying a communication
in the network between a network node entity and the target entity.
Advantageous Effects of Invention
[0051] According to the Invention, one or more of the above-mentioned problems is/are
ameliorated or overcome.
Brief Description of Drawings
[0052] The present invention is illustrated by way of example, and not by way of limitation,
in the figures of the accompanying drawings, in which like reference numerals refer to
similar elements and in which:
[fig. 1]Fig. 1 represents a conventional network according to the prior art;
[fig.2]Fig. 2 represents a conventional radio interface protocol;
[fig.3]Fig. 3 represents LTE/UMTS sub-layers of layers 2 and 3;
[fig.4]Fig. 4 represents radio bearers used for communications;
[fig.5]Fig. 5 illustrates the path of data during a relay;
[fig.6]Fig. 6 is a flowchart representing the steps of a method for configuration of a
relay according to an embodiment of the invention;
[fig.7]Fig. 7 represents the data relaying according to an embodiment of the invention;
[fig.8A]Fig. 8A is a flowchart representing the configuration of a relay in a general
case;
[fig.8B]Fig. 8B is a flowchart representing the configuration for NAS signalling of a
relay in an "above MAC" case;
[fig.8C]Fig. 8C is a flowchart representing the configuration for NAS signalling of a
relay in an "above RLC" case;
[fig.9A]Fig. 9A is a flowchart representing the configuration for data relaying of a
relay in a general case;
[fig.9B]Fig. 9B is a flowchart representing the configuration for data relaying of a
relay in an "above MAC" case;
[fig.9C]Fig. 9C is a flowchart representing the configuration for data relaying of a
relay in an "above RLC" case;
[fig. 1OA]Fig. 10A is a flowchart representing data relaying in an "above MAC" case in
the downlink direction;
[fig. 10B]Fig. 10B is a flowchart representing data relaying in an "above RLC" case in
the downlink direction;
[fig. 1l]Fig. 11 is a flowchart representing data relaying in an "above MAC" case in the
uplink direction.
Description of Embodiments
[0053] Referring to Fig. 4, a network node entity such as for example a base station (an
evolved NodeB (eNB) for example in a LTE network) is establishing a bearer con
figuration for a user equipment UER to be used as a relay between the network node
entity eNB and a target entity UET which can be a user equipment or a relay node (for
example another UE relay, or a base station).
[0054] When the target UET needs the relay of the relay UER, radio bearers (RB) have to be
adapted in order to carry out control and transmit user data from the eNB to the UET
(in the downlink case) or from the UET to the eNB (in the uplink case). In the
following description, the downlink case will be described but the same reasoning can
be symmetrically applied for the uplink case.
[0055] In an embodiment, the relay is fulfilled by creating two radio bearers: one radio
bearer between UET and UER and one radio bearer between UER and eNB. These
bearers are relayed in UER. The relay can be processed in the Packet Data Con
vergence Protocol (PDCP) sub-layer (the higher sub-layer included in layer 2) or in the
Radio Link Control (RLC) sub-layer.
[0056] UER relays UET to eNB traffic either above the Media Access Control (MAC) sub
layer, or above the Radio Link Control (RLC) sub-layer (both of these sub-layers are
included in so-called "Layer 2" (L2)). The security of the traffic is ensured by the end
to end PDCP layer between UET and eNB. Therefore, users cannot have access to the
relayed data because these data do not reach layers 4 to 7 (application layers being
easier to access).
[0057] Usually (in the case of a mere communication between an eNB and a UER without
relay), some messages are dedicated to establish the communication between the eNB
and a user equipment. For example, Radio Resource Control (RRC) signaling
messages are usually used for connection establishment and release or for radio bearer
establishment/reconfiguration and release. Therefore, RRC signaling messages are
inter alia used for the establishment and reconfiguration of radio bearers between an
eNB and a UE.
[0058] In an embodiment, RRC signaling messages are used to establish, configure or r e
configure radio bearers used for the relay. These radio bearers will carry the communication
between the eNB and the UER and between the UER and the UET.
[0059] As the UER is a not a dedicated device only used for relaying, RRC signaling
messages have to be modified for the UER so that the UER can interpret that it will
have to process as a relay for some radio bearers. Therefore, new information element
has to be added in the RRC signaling messages. For example, the new information
elements can be included in the eNB to UER RRC Connection Reconfiguration
message.
[0060] Fig. 4 highlights differences between the usual use of radio bearers without relay
(UER <-> network c-plane and u-plane in Fig. 4) and the use of radio bearers with the
relay of UER (UET <-> network c-plane & u-plane in Fig. 4).
[0061] When the relay is processed, the radio bearer used between the eNB and the UER
contains added information in order to perform the relay. As specified above, the e s
tablishment of the radio bearers can be processed by adding new information in the
RRC signaling message. As the RRC handles the control plane signaling of Layer 3,
the establishment of the radio bearers for the relay is processed by a layer 3 protocol.
The establishment is processed at layer 3 but the relay of data is processed at layer 2,
optionally above the MAC sub-layer or above the RLC sub-layer, according to two al
ternative implementations described below.
[0062] Fig. 5 shows the path of data relayed through UET, UER and eNB layers. As
previously described, the data are relayed above MAC or above RLC sub-layers
(represented in dotted line in Fig. 5).
[0063] Before any relaying, signaling information between UEs has to be set up so as data
related to UET can be conveyed via a relay UER. For example, the signaling in
formation can be related to a signaling radio bearer.
[0064] In an embodiment, the configuration of the relay is processed in two steps. One step
to configure the mapping for data relaying towards UET and one step to configure
radio bearers used to carry those data.
[0065] Fig. 6 represents the configuration process to initiate the relay. The mapping step and
the radio bearer configuration step are not processed in a specific order: the mapping
step can be processed before, after or in the same time as the radio bearer configuration
step.
[0066] The core network CN initiates the procedure by setting-up a bearer configuration for
the eNB. This step fills the field eRAB setup request (eRAB for evolved radio bearer)
which is sent to the eNB. For example eRAB setup request includes the eRAB identi
fication and/or the Quality of Service (QoS).
[0067] Then, the eNB generates control information needed to configure the relay at UER.
This information includes mapping configuration information and radio bearer con
figuration information. For example:
- an identifier LC_ID for mapping a logical channel between UER and UET,
- a radio bearer configuration parameters set "UER-UET RB config" for a con
figuration of a radio bearer between UER and UET and
- a radio bearer configuration parameters set "UER-eNB RB config" for a con
figuration of a radio bearer between UER and eNB,
can be generated.
[0068] Then, those data are sent to UER.
Then, UER performs the logical channel mapping and the radio bearer configuration.
For example, an identifier LC_ID_R can be assigned to the logical channel between
eNB and UER so as to designate the logical channel between UER and UET having
the identifier LC_ID. These identifiers LC_ID_R and LC_ID are included in a RRC
signaling message, providing thus information to perform the logical channels
mapping. The UER-UET RB configuration and UER-eNB configuration parameters in
the RRC signaling message further provide information for the radio bearers con
figuration.
[0069] After the configuration, the data relaying can be performed through UER layer 2.
It should be understood that the identifier LC_ID can designate the logical channel
between UER and UET but the identifier LC_ID_R, when received at UER with data
from eNB and intended to UET, is interpreted by UER as designating the logical
channel between UER and UET, for forwarding the received data. Reversely, the
identifier LC_ID_R can designate the logical channel between UER and eNB but the
identifier LC_ID, when received at UER with data from UET and intended to eNB, is
interpreted by UER as designating the logical channel between UER and eNB, for
forwarding the received data.
[0070] In brief, referring to Fig. 6, in a first step SI, the core network CN defines a setup of
the radio bearers configuration and sends to the eNodeB (eNB) a request Req for a
eRAB setup. Upon reception of the request Req, in a second step S2, the eNB
generates:
- the identifiers LC_ID_R and LC_ID, for the logical channels mapping,
- the parameters set UER_UET RB config, for the configuration of the radio bearer
between the target entity UET and the relay entity UER, and
- the parameters set UER_eNB RB config, for the configuration of the radio bearer
between eNB and the relay entity UER.
[0071] The identifier and the parameters sets are then sent to the relaying entity UER (arrow
referenced "Param" in Fig. 6), for example in the content of a message such as an RRC
Connection Reconfiguration message (RRC for "Radio Resource Control"). Advan
tageously, the kind of such a message already exists and the invention can be im
plemented without any need of deep modifications. In step S3, the relaying entity UER
performs the mapping of a logical channel between the UER and the UET, this logical
channel having an identifier LC_ID. Moreover, radio bearers are configured between
the target entity and the relay entity (UER-UET RB), and between the eNodeB and the
relay entity (UER-eNB RB).
[0072] After this configuration, the system is designed so that data to be transferred between
the eNB and the target UET are relayed through the relay UER as described hereafter
and shown on Fig. 7.
[0073] Fig. 7 depicts the data relaying. Layer 2 (L2) is subdivided in three sub-layers: r e
spectively PDCP, RLC and MAC sub-layers.
At each level, two entities (eNB and UER for example) interact by means of layer
protocol (PDCP, RLC or MAC protocol) by transmitting Protocol Data Units (PDU).
This "transmission" is an abstraction in fact (actually, data is encapsulated through
lower layers to be physically transmitted through the physical layer, e.g. layer 1).
[0074] In an embodiment, data is relayed above the MAC sub-layer. This means that MAC
PDUs are forwarded at the RLC sub-layer level.
[0075] In another embodiment, data is relayed above the RLC sub-layer. This means that
RLC PDUs are forwarded at the PDCP sub-layer level. This embodiment is rep
resented by dotted lines in Fig. 7.
[0076] In both cases, data are mapped:
- thanks to the identifier "LC_ID_R" between UER and eNB, and
- thanks to the identifier "LC_ID" between UER and UET.
[0077] As the configuration steps SI, S2, S3 provide the mapping configuration explained
above, the relay entity UER is able to interpret that data identified by "LC_ID_R" are
to be forwarded to the target entity UET (which can be a terminal in the network, or
another relay node for hoping a communication through several relay nodes for
example).
[0078] In an embodiment, the UER is used for relaying of Non-Access Stratum (NAS)
signaling with the UET. Non-Access Stratum signaling allows mobility of the UE
through different nodes. In such an embodiment, the UET is signaled even if it is out of
eNB range.
[0079] As described above, relay can be done above MAC sub-layer or above RLC sub
layer. Fig. 8A globally depicts relay of NAS signaling and Figs. 8B and 8C r e
spectively describe the above MAC and above RLC case. These Figs provide details
for implementation of the present invention, particularly for implementation with
respect to 3GPP LTE standard.
[0080] In Fig. 8A, a Mobility Management Entity (MME), which can be part of the core
network CN for LTE, sets up the bearer configuration. This set-up allows the
transmission of NAS PDU (NAS is a layer 3 sub-layer). With such information, the
UER provides the mapping configuration and the radio bearer configuration for the
relay (CONFIG in Fig. 8A). This step allows adaptation of RRC Connection Recon
figuration for relay which includes new information element (NIE).
[0081] Figs. 8B and 8C point out differences between above MAC relaying and above RLC
relaying. In the 3GPP LTE implementation, this difference is particularly visible in the
(UER-UET) SRB(2) config field.
[0082] In a further embodiment, relaying is performed because the UET has requested com
munication towards the network via the UER or because the UET, while commu
nicating with the network, has moved out of coverage of the network. As described
above, relaying can be done above the MAC sub-layer or above the RLC sub-layer.
Fig. 9A globally shows the configuration procedure for the relay of data and Figs. 9B
and 9C respectively show the above MAC and the above RLC cases. These Figs
provide details for implementation of the present invention, particularly for imple
mentation with respect to 3GPP LTE standard. Figs. 9B and 9C point out differences
between above MAC relaying and above RLC relaying. In the 3GPP LTE imple
mentation, this difference is particularly visible in the (UER-UET) RB config field.
[0083] Figs. 10A and 10B respectively describe a possible implementation to perform data
relaying in the above MAC case and in the above RLC case. A Service Data Unit
(SDU) is a specific unit of data that has been passed down from an OSI layer to a
lower layer, and which the lower layer has not been encapsulated yet into a protocol
data unit (PDU). As MAC sub-layer is a lower sub-layer than RLC sub-layer, MAC
PDU is included in RLC PDU. Flags are included in MAC PDU for the UER to relay
data.
[0084] In Figs. 10A to 11, FLAG 2 is used to indicate to UER that MAC data contained in
this MAC PDU are intended to the UET via relay. FLAG 1 is the 'usual' flag used
without relay so that the UET receives data contained in MAC PDU as if these data
come directly from the eNB. As previously described, data are mapped thanks to
FLAG 2 between the UER and the eNB and thanks to FLAG 1 between the UER and
the UET. As the configuration steps provide the mapping configuration, the UER is
able to interpret and simply forward data identified by FLAG 2. These Figs provide
details for implementation of the present invention, particularly for implementation
with respect to 3GPP LTE standard. Fig. 11 provides details for implementation of the
present invention in the uplink case, particularly for implementation with respect to
3GPP LTE standard.
[0085] Therefore, in brief, the present invention proposes, in an embodiment, to provide the
Radio Access Network (RAN) with a logical channel mapping configuration along
with radio bearers configuration for data relaying towards a target entity UET with the
use of a relay entity UER. In an embodiment, the invention provides additional information
meaning that the radio bearers configuration is performed for relaying
purpose (addition of an identifier LC_ID for example). Such information, at least, can
be included in a pre-existing RRC Connection Reconfiguration message (RRC for
"Radio Resource Control").
[0086] In an embodiment, the invention provides an "above MAC" (plain line of Fig. 7) or
an "above RLC" (dashed line of Fig. 7) data relaying configuration, according to a
choice of optimization which can be, for example, decided at first in the network. Of
course, such a choice can depend also on the relay entity capacities and/or con
struction.
Furthermore, if RAN does not provide any above RLC configuration, then the UER
can perform above MAC data relaying. This choice of implementation in the UER can
be dictated by the radio bearer quality of service.
[0087] For the downlink direction, the relay entity UER forwards the data received on a
logical channel flagged with a specific identifier (for example LC_ID as previously
described) to a next hop logical channel as per a logical channel mapping configuration
previously defined. Unless configured by the network as described above, "above
RLC" or "above MAC" data relaying can be an option according to the UER capacities
and/or construction, as indicated above. If UER performs " above RLC " data relaying,
then PDCP data is conveyed from UER to a next hop UET (which can be a relay for a
further target). If UER performs " above MAC " data relaying, then RLC data is
conveyed to next hop UET.
[0088] For the uplink direction, the UER transparently (i.e. without decoding) forwards the
data received on the logical channel towards the network using the logical channel
identified with a specific identifier (LC_ID for example) of the configured relay bearer
as per the previously received logical channel mapping configuration.
[0089] Of course, a same UE can relay several communications. Therefore, several
identifiers LC_ID can be used to that end (with a logical channel for each UE target to
be reached). Moreover, a same communication can be relayed by several UEs
(generating several successive logical channels) and several identifiers LC_ID can be
used to that end also.
[0090] The present invention can also be embedded in a computer program product, which
includes all the features enabling the implementation of the methods described herein,
and which, when loaded in an information processing system (for example in a user
equipment UER), causes the information processing system. Computer program means
or computer program in the present context mean any expression, in any language,
code or notation, of a set of instructions intended to cause a system having an in
formation processing capability to perform a particular function either directly or after
the conversion to another language. Such a computer program can be stored on a
computer or machine readable medium allowing data, instructions, messages or
message packets, and other machine readable information to be read from the medium.
The computer or machine readable medium may include non- volatile memory, such as
ROM, Flash memory, Disk drive memory, CD-ROM, and other permanent storage.
Additionally, a computer or machine readable medium may include, for example,
volatile storage such as RAM, buffers, cache memory, and network circuits. Fur
thermore, the computer or machine readable medium may include computer or
machine readable information in a transitory state medium such as a network link and/
or a network interface, including a wired network or a wireless network, that allow a
device to read such computer or machine readable information.
[0091] Expressions such as "comprise", "include", "incorporate", "contain", "is" and "have"
are to be construed in a non-exclusive manner when interpreting the description and its
associated claims, namely construed to allow for other items or components which are
not explicitly defined also to be present. Reference to the singular is also to be
construed in be a reference to the plural and vice versa.
[0092] While there has been illustrated and described what are presently considered to be the
preferred embodiments of the present invention, it will be understood by those skilled
in the art that various other modifications may be made, and equivalents may be sub
stituted, without departing from the true scope of the present invention. Additionally,
many modifications may be made to adapt a particular situation to the teachings of the
present invention without departing from the central inventive concept described
herein. Furthermore, an embodiment of the present invention may not include all of the
features described above. Therefore, it is intended that the present invention not be
limited to the particular embodiments disclosed, but that the invention include all em
bodiments falling within the scope of the invention as broadly defined above.
[0093] A person skilled in the art will readily appreciate that various parameters disclosed in
the description may be modified and that various embodiments disclosed and/or
claimed may be combined without departing from the scope of the invention.
[0094] incorporation by reference>
This application is based upon and claims the benefit of priority from European
Patent Application No. EP 12306301.8, filed on October 19, 2012, the disclosure of
which is incorporated herein in its entirety by reference.
PCT/JP2013/004578
Claims
A method for relaying a communication in a network, wherein a user
equipment relays a communication between a network node entity and
a target entity, the method comprising the steps:
generating a logical channel at least between the user equipment relay
and the target entity, and assigning at least one identifier to said logical
channel, and
upon reception from the network node entity, at the user equipment
relay, of data received with said identifier, the user equipment relay
forwards the received data to the target entity.
The method for relaying a communication in a network according to
claim 1, further comprising the steps:
generating a logical channel between the user equipment relay and the
network node entity, and assigning an identifier to said logical channel,
and
upon reception from the target entity, at the user equipment relay, of
data received with said identifier, the user equipment relay forwards the
received data to the network node entity.
The method for relaying a communication in a network according to
claim 1 or 2, wherein the step of generating said logical channel
comprises configuring:
a radio bearer between the user equipment relay and the network node
entity, and
a radio bearer between the user equipment relay and the target entity.
The method for relaying a communication in a network according to
claim 3, comprising the step of receiving from the network node entity
the identifier of the logical channel, and parameters for setting up said
radio bearers.
The method for relaying a communication in a network according to
claim 4, wherein said identifier and parameters are included in a
message of a type of a "Radio Resource Control" signalling message
sent from said network node entity to the user equipment relay.
The method for relaying a communication in a network according to
claim 5, wherein said signalling message is a "Radio Resource Control
Connection Reconfiguration" message.
The method for relaying a communication in a network according to
any one of claims 1 to 6, wherein said data are relayed through the user
PCT/JP2013/004578
equipment relay according to a protocol of a layer 2 in an Open
Systems Interconnection model.
The method for relaying a communication in a network according to
claim 7, wherein said data are relayed through the user equipment relay
according to a protocol of an above MAC layer.
The method for relaying a communication in a network according to
claim 8, wherein said logical channel identifier is comprised in a MAC
Protocol Data Unit.
The method for relaying a communication in a network according to
claim 7, wherein said data are relayed through the user equipment relay
according to a protocol of an above RLC layer.
The method for relaying a communication in a network according to
claim 10, wherein said identifier is comprised in a RLC Protocol Data
Unit.
The method for relaying a communication in a network according to
claim 7 or 11, wherein said protocol layer to be used for relaying at the
user equipment relay is configured by the network.
The method for relaying a communication in a network according to
claim 12, wherein information related to a used protocol layer con
figuration is included in a message of a type of a "Radio Resource
Control" signalling message sent from said network node entity to the
user equipment relay.
A computer program product, comprising instructions for performing
the method as claimed in anyone of the preceding claims, when run by
a processor.
A user equipment comprising means for relaying a communication in a
network, between a network node entity and a target entity, the user
equipment further comprising means for:
upon reception from the network node entity of data received with an
identifier of a logical channel between the user equipment relay and the
target entity, the user equipment relay forwards the received data to the
target entity.
The user equipment according to claim 15, further comprising means
for generating a logical channel at least between the user equipment
relay and the target entity, and assigning at least one identifier to said
logical channel.
A base station comprising:
means for determining a user equipment for relaying a communication
WO 2014/061180 PCT/JP2013/004578
in a network between a network node entity and a target entity, and
means for further determining a logical channel between the user
equipment relay and the target entity, and assigning at least one
identifier to said logical channel.
[Claim 18] The base station according to claim 17, further comprising means for
sending a "Radio Resource Control" signalling message comprising
said identifier.
[Claim 19] A core network comprising means for determining data related to at
least a logical channel between a user equipment relay and a target
entity, said user equipment being intended to be used as a relay for
relaying a communication in the network between a network node
entity and the target entity.